US 4,052,704 AGranted

Apparatus for reordering the sequence of data stored in a serial memory

AssigneeInternational Business Machines Corporation

InventorPeter Anthony Franaszek

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Abstract

This memory management system provides an improved search logic for locating pages of data stored parallel-by-bit, serially-by-page in a shift register memory and for moving those pages to a position at the head of the file. Searching alternates between forward and reverse with a first direction change occurring when the head of the file occupies an input/output station in the memory and a second change occurring when the last of a plurality of pages identified for search at the first reversal position is found. The page numbers of three sought data pages are entered into three search registers and compared with the page number of each page as it is shifted into the input/output station of the memory. A page number is replaced when the page is found. Page numbers are marked with a binary one upon each direction change at the first position and with a binary zero at each replacement of a page number at other than that position. The data loop includes four parking registers which may be selectively excluded from the loop so as to park the successive pages as they are found in the search. As a reverse feeding moves the head of the file proximate to the input/output station, the pages stored in the parking registers are inserted into the data stream at the head of the file.

Claims8

Dependent claims

In a memory management system for a serial shift register type of memory having at least one station through which successive pages of date, including a page number, may be bidirectionally shifted for sensing of the data and operative to reorder the sequence of the stored pages to group the most recently accessed pages at the head of the file, the improvement comprising:

a. register means for storing a plurality of page numbers for search;
b. means operative when the head of the file resides at said station for initiating a data shift in a first direction through said shift register memory and for marking the page numbers in said register means with a first significant indicia;
c. means operative to compare said stored page numbers with each of the page numbers as they are shifted in either direction through said station and producing an equality signal upon a match;
d. means operative responsive to said equality signal for replacing the matching page number in said register and marking the replacement with a second significant indicia;
e. means operative responsive to the presence of all said second indicia in said register for reversing the direction of search;
f. means operative responsive to each of said equality signals for diverting the pages in said shift register memory whose page numbers matched those in said register means from a main shifting path into a parking means;
and
g. means operative to reinsert the parked pages from said parking means into the main shifting path when the head of the file is proximate said station.

5 more elements

Dependencies are inferred from the claim text.